摘要:以两种常见园林观赏草：白穗狼尾草（Pennisetum alopecuroides ‘White’）和拂子茅（Calamagrostis epigeios）作为试验材料，利用开顶箱（OTCs）模拟法，研究了不同高浓度臭氧（O₃，EO）：80 nmol/mol（EO-80）、120 nmol/mol（EO-120）和160 nmol/mol（EO-160）下两种观赏草叶片逆境生理特征的变化规律。结果表明：（1）短期（7 d）内随O₃浓度增加，白穗狼尾草叶绿素和类胡萝卜素含量较对照呈下降趋势，拂子茅较对照无显著变化。（2）在EO-120、EO-160下处理7 d时，两种观赏草叶片的净光合速率（P_n）和气孔导度（g_s）较对照显著下降，且白穗狼尾草下降的幅度均大于拂子茅。（3）不同高浓度O₃胁迫下，两种观赏草叶片丙二醛（MDA）含量较对照均有所升高，其中在EO-160下处理21 d时白穗狼尾草和拂子茅叶片MDA含量分别增加30.2%（P<0.05）和13.5%（P>0.05），表明在EO-160浓度胁迫下白穗狼尾草受到的膜脂过氧化伤害大于拂子茅。（4）在EO-120和EO-160下处理21 d时，白穗狼尾草叶片可溶性蛋白含量较对照分别显著下降24.2%和43.1%，而拂子茅较对照分别下降19.0%和22.9%（P<0.05）。（5）与对照组相比，高浓度O₃下两种观赏草叶片的过氧化物酶（POD）活性随胁迫时间延长呈下降趋势，超氧化物歧化酶（SOD）活性呈先升后降。（6）综合以上生理特征比较及主成成分分析表明，佛子茅比白穗狼尾草更耐O₃，前者在O₃高污染地区可能会有更高的应用价值。



Abstract:With the development of urbanization, ozone (O₃) pollution is becoming more and more concerned in the world including China in recent years. Ornamental grass species play an important role in urban greening and landscape design for urban ecological construction. However, little information is known about the response characteristics of ornamental grass species to O₃ pollution. An experiment was conducted to study the changes of the physiological characteristics in leaves of two common landscape ornamental grass species:Pennisetum alopecuroides ‘White’ and Calamagrostis epigeios exposed to the different concentrations of elevated O₃ (EO):80 nmol/mol (EO-80), 120 nmol/mol (EO-120) and 160 nmol/mol (EO-160) in open top chambers (OTCs). The results showed that:(1) during the short term (7 d), with the increase of O₃ concentrations, the contents of chlorophyll and carotenoids in leaves of P. alopecuroides ‘White’ showed a decreasing trend compared with the control group, and there was no significant change for C. epigeios. (2) Net photosynthetic rate (P_n) and stomatal conductance (g_s) of the two ornamental grass species leaves decreased significantly under EO-120 and EO-160 for 7 d, compared to the control. In addition, the decreasing degrees of these photosynthetic parameters in leaves of P. alopecuroides ‘White’ were larger than those of C. epigeios. (3) Under elevated O₃ concentrations, malondialdehyde (MDA) content in leaves of the two ornamental grass species showed an increasing trend compared with that under the control. When treated with EO-160 for 21 d, MDA content increased by 30.2% in the leaves of P. alopecuroides ‘White’ (P<0.05), and 13.5% in leaves of C. epigeios (P > 0.05), which indicated that P. alopecuroides ‘White’ suffered from a higher injury of membrane lipid peroxidation than C. epigeios under EO-160. (4) When treated with EO-120 and EO-160 for 21 d, soluble protein content in leaves of P. alopecuroides ‘White’ decreased significantly by 24.2% and 43.1% compared with the control, respectively; and decreased significantly in leaves of C. epigeios by 19.03% and 22.9%, respectively (P<0.05). (5) Peroxidase (POD) activity in leaves of the two ornamental grass species decreased with the increase of O₃ concentrations, and the activity of superoxide dismutase (SOD) first increased and then decreased. (6) Based on the comparison of physiological characteristics and the analysis of principal components, we found that that C. epigeios was more tolerant to O₃ than P. alopecuroides ‘White’, and the former could show higher value of application than the latter, especially in O₃-polluted urban areas.





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